1. Technical Field
The present invention relates to an inertial sensor.
2. Description of the Related Art
Recently, an inertial sensor has been used in various fields, for example, the military, such as an artificial satellite, a missile, an unmanned aircraft, or the like, vehicles, such as an air bag, electronic stability control (ESC), a black box for a vehicle, or the like, hand shaking prevention of a camcorder, motion sensing of a mobile phone or a game machine, navigation, or the like.
The inertial sensor generally adopts a configuration in which a mass body is bonded to a flexible substrate such as a membrane, or the like, so as to measure acceleration and angular velocity. Through the configuration, the inertial sensor may calculate the acceleration by measuring inertial force applied to the mass body and may calculate the angular velocity by measuring Coriolis force applied to the mass body.
In detail, a process of measuring the acceleration and the angular velocity by using the inertial sensor will be described in detail below. First, the acceleration may be obtained by Newton's law of motion “F=ma”, where “F” represents inertial force applied to the mass body, “m” represents a mass of the mass body, and “a” is acceleration to be measured. Therefore, the acceleration a may be obtained by sensing the inertial force F applied to the mass body and dividing the measured inertial force F by the mass m of the mass body that is a predetermined value. Meanwhile, the angular velocity may be obtained by Coriolis force “F=2 mΩ·v”, where “F” represents the Coriolis force applied to the mass body, “m” represents the mass of the mass body, “Ω” represents the angular velocity to be measured, and “v” represents the motion velocity of the mass body. Among others, since the motion velocity v of the mass body and the mass m of the mass body are values that are known in advance, the angular velocity Ω may be obtained by sensing the Coriolis force (F) applied to the mass body.
As described above, in order to sense the inertial force (F) or the Coriolis force (F) applied to the mass body, the displacement of the membrane bonded to the mass body needs to be accurately measured. The displacement of the membrane is measured using a piezoelectric material and a sensing electrode formed on the membrane. However, in the case of the inertial sensor according to the prior art, there has not yet been a method of increasing measurement sensitivity of the displacement of the membrane due to limitations in a design, or the like.